A dual-purpose power combiner/divider is required for a solid state power amplifier design. Current technology for solid state combiner/divider designs uses microstrip, stripline, slabline, suspended substrate stripline, or waveguide designs. For example, Wilkinson power splitters, rat race, quadrature 90-degree hybrid, and reactive-tee are all types of splitters, combiners, and dividers that use microstrip, stripline, slabline, and suspended substrate stripline designs. Free-emitting conical radial power combiners and magic-tees use waveguide technology. Both the Wilkinson and wired radial power combiners/dividers are a form of a branching transmission line network, also called a corporate feed network.
The Wilkinson power combiner/divider is typically limited in how much power it can handle and dissipate. Its isolation resistors and the mode of propagation limit the power handling capability of the device versus waveguide architecture. For numerous power splits, a Wilkinson splitter has comparatively higher insertion loss than a ridged radial power combiner/divider device. Additionally, the Wilkinson power combiner/divider is highly frequency-dependent for isolation. As the frequency increases or decreases from the matched center frequency, the quarter-wave architecture limits the cancellation effects that are required for a Wilkinson device to maintain isolation. Because of this, additional quarter-wave sections and resistors may be added to increase the bandwidth, which may result in higher loss, increase in package size, and potentially lower power handling capabilities with added costs.
Existing radial power combiners use stripline, microstrip, slabline, and suspended substrate stripline designs. These technologies have comparatively higher insertion loss as compared to a ridged waveguide radial power combiner/divider. Furthermore, stripline, microstrip, slabline and suspended substrate stripline typically do not have the peak or average power handling characteristics of a ridged waveguide structure, thus significantly reducing the ability to produce high enough power to replace existing high power vacuum tube amplifiers.
The phase for both existing radial power combiners and Wilkinson combiner/dividers are highly dependent upon machining tolerances, or they will require additional RF+ tuning. This, in return, produces the potential for a considerable tolerance stack up that degrades the phase match across each port. The phase match of the network becomes more complicated as the number of ports increase; in other words, as the number of ports increase in a branching transmission line, the branching network gets larger, which increases how much the phasing will deviate between ports due to slight geometric changes in the branching structure and quarter wave transforms. Phase matching is critical for combining and dividing structures. Signals that are out of phase are prone to cancel each other out, multiply the signal, or decrease the signal strength. Depending on how broadband the combiner/divider is, a change in frequency could create inconsistent energy transfer. The decrease in signal strength reduces the efficiency of the amplifying network. A free-emitting conical radial power combiner shares many of the same disadvantages as the branching transmission line networks described above. However, where a free-emitting radial power combiner lacks in cross-port isolation, it has a significant improvement in cross port phase matching and insertion loss performance, which is also not limited by the quantity of ports.
Accordingly, there is a continued need in the art for an n-way power combiner/divider that minimizes loss while maintaining a matched condition on all ports. An N-way radial power combiner/divider that has low insertion loss, high power handling, good isolation, and phase matching may allow for the design of efficient High-Power Solid State Amplifiers that are fault-tolerant. The efficiency of an N-way, Ridged Waveguide, Radial Power Combiner/Divider does not degrade substantially if one or more modules fail, allowing continued operation, often referred to as graceful degradation.